wifi: ath11k: Add support to get power save duration for each client

Add support to get the following power save information through debugfs interface,

 * Current ps state of the peer
 * Time duration since the peer is in power save
 * Total duration of the peer spent in power save

Above information is helpful in debugging the issues with power save clients.

This patch also add trace log support for PS timekeeper to track the PS state
change of the peers alongs with the peer MAC address and timestamp.

Use the below commands to get the above power save information,

To know the time_since_station_in_power_save:
cat /sys/kernel/debug/ieee80211/phyX/netdev:wlanX/stations/
XX:XX:XX:XX:XX:XX/current_ps_duration

To know power_save_duration:
cat /sys/kernel/debug/ieee80211/phyX/netdev:wlanX/stations/
XX:XX:XX:XX:XX:XX/total_ps_duration

To reset the power_save_duration of all stations connected to AP:
echo 1 > /sys/kernel/debug/ieee80211/phyX/ath11k/reset_ps_duration

To enable/disable the ps_timekeeper:
echo Y > /sys/kernel/debug/ieee80211/phyX/ath11k/ps_timekeeper_enable
Y = 1 to enable and Y = 0 to disable.

To record PS timekeeer logs after enabling ps_timekeeper:
trace-cmd record -e ath11k_ps_timekeeper

Tested-on: Tested-on: IPQ8074 WLAN.HK.2.5.0.1-00991-QCAHKSWPL_SILICONZ-1

Signed-off-by: Venkateswara Naralasetty <quic_vnaralas@quicinc.com>
Signed-off-by: Tamizh Chelvam Raja <quic_tamizhr@quicinc.com>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://lore.kernel.org/r/20220725054601.14719-1-quic_tamizhr@quicinc.com